Not to worry, we've got 4013053939 and 633010401. Let's get to adding them!

Step 1: We'll start by adding the digits 9 & 1 in column 1 and get 10.
We'll write down the last digit 0 and carry the 1 to the next column.

Step 2: We'll start by adding the digits 3 & 0 in column 2 and get 4.

Step 3: We'll start by adding the digits 9 & 4 in column 3 and get 13.
We'll write down the last digit 3 and carry the 1 to the next column.

Step 4: We'll start by adding the digits 3 & 0 in column 4 and get 4.

Step 5: We'll start by adding the digits 5 & 1 in column 5 and get 6.

Step 6: We'll start by adding the digits 0 & 0 in column 6 and get 0.

Step 7: We'll start by adding the digits 3 & 3 in column 7 and get 6.

Step 8: We'll start by adding the digits 1 & 3 in column 8 and get 4.

Step 9: We'll start by adding the digits 0 & 6 in column 9 and get 6.

Step 10: We'll start by adding the digits 4 & 0 in column 10 and get 4.

So, 4013053939 + 633010401 = 4646064340.

